Is Colorado the next California? Oh, how Democrats hope so -- they want one, two, many Californias.

A recent bout of polls show President Bush pulling ahead in the traditionally Republican-leaning battleground states that he must win, except for Colorado, which remains nip and tuck. The Rocky Mountain State is relatively close for the same reason -- at least partly -- that California has been lost to the GOP in presidential elections: ever-increasing numbers of Latino immigrants. That's why Republican stalwarts Nevada and Arizona are slowly shifting too.

Outside the merits of the immigration issue -- its costs, its implications for security and national cohesion -- the partisan dynamic is clear: Higher levels of Latin American immigration benefit the Democrats, while digging an ever-deeper demographic hole for Republicans. Pro-immigration conservatives fool themselves into believing that being pro-immigration will make it possible for the GOP to convert large numbers of Hispanic voters to their side. This is a party strategy that could have been crafted in Oregon, since it amounts to a kind of partisan assisted suicide.

New immigrants are poor, and Republicans have never, as a basic fact of political life, been good at attracting poor voters. New immigrants settle in large urban areas and older or low-income suburbs. Because these areas tend to be dominated by Democrats, it is Democratic organizations that will introduce them to politics, providing an immense benefit to their own party. "If you add all these considerations up," says James Gimpel, a University of Maryland professor who has studied the issue, "new immigrants just make great fodder for building the Democratic Party."

For the Democrats, then, bringing new Latin American immigrants into the country is like importing more Upper West Siders or more sociology Ph.D.s -- it adds directly to the Democratic voter rolls. And once immigrants are signed up there, they are unlikely to leave, since initial partisan impressions are long-lasting. "Everyone is shaped by their environment," says Gimpel. It is one reason that Jews, despite their high income and levels of education, vote like Puerto Ricans, as someone once famously put it.

The latest data shows that Democrats have a 2-1 registration advantage over Republicans among Hispanics. In the 2002 midterm elections, when optimistic Republicans told themselves they had performed particularly well among Hispanics, Latinos voted 65 percent Democratic and 32 percent Republican in Senate races. In gubernatorial races, the split was essentially the same. If a 2-1 landslide against you is progress, you are in trouble.

With its amnesty proposal at the beginning of the year, the Bush administration hoped to win more Hispanic support, but to no avail. "The notion that you can float some sort of amnesty, and low-income, poorly educated voters come on board is fantasy," says Gimpel, who has just authored a report for the Center for Immigration Studies on Latino voting patterns. Latinos mainly vote on the same issues as everyone else, meaning they vote like most other poor, Democratic-leaning voters. According to a Pew study, Latinos rate immigration reform 11th in terms of its importance as an issue.

Bush has been operating on a flawed theory of his own performance among Hispanics in his 1998 gubernatorial re-election in Texas. Yes, Bush did much better than Republicans usually do among Hispanics. But that is mostly because in his landslide victory many Hispanic voters stayed home, which increased the share of more-affluent, Republican-leaning Latinos in the Hispanic electorate. "There is a big difference between increasing your share of the Hispanic vote based on low turnout and increasing it on the basis of conversion," says Gimpel.

Whether Bush wins or not this year, the Republican Party is in for intramural battles in the run-up to 2008, over the size of government, over foreign policy, and -- by rights -- over immigration. Colorado (17 percent Hispanic) is still a long way from California (32 percent), but the trend is clear. As for the Democrats, their attitude toward current levels of immigration should be "bring it on," and bring them in.